Off-peak water heating system



C. M. OSTERIHELD OFF-PEAK WATER HEATING SYSTEM Filed Nov. 7, 1940 INVENTOR CLARK Own/45w ATTO RNEY Patented Dec. 16, 1941 OFF-PEAK WATER HEATING SYSTEM Clark M. OsterheltLStonghton, 'Wla., assignmto -McGraw Electric Com poration Delaware pany, Elgin, 111., a cor- Appiication November 7, 1940, Serial No. 364,638

6 Claims.

My invention relates to electric water heating systems and particularly to off-peak water heating systems.

An object of my invention is to provide a relatively simple time-controlled means for energizing either momentarily or continuously for a fixed length oi. time, the control element of a hot water electric heating system.

Another object of my invention is to provide a timing means adapted to be positioned relatively closely to a hot water tank, 'such as may be used in domestic installations, and eil'ective to energize a control element to ensure that a predetermined fractional part of the water content of the tank shall be hot during the daylight hours and that substantially all of the water in the tank shall be hot at the start of the daylight period.

Other objects of my invention will either be apparent from a description of my invention or will be pointed out hereinafter, particularly in the appended claims.

, In the single sheet of drawings,

Figure 1 is a schematic diagram of connections of a system embodying my invention, shown as applied to the usual domestic hot water tank,

and,

Fig. 2 is a view in front elevation of a modified form of one part of the device particularly embodyingmy invention.

My system is shown as operatively associated with an ordinary hot water tank ll having a cold water inlet pipe it connected thereto at its bottom end and a hot water outlet pipe l5 connected thereto at its upper end. I may provide ing the tank II and held in place by an outer .casing l9. All of these elements are old and well known in the art and form present invention.

I provide an electric heater 2| which, for simplicitys sake, is shown as being positioned on the tank ll near the bottom end thereof and this heater may be positioned in a tunnel or annular housing 23 and, for illustrative purposes only, I may here state that one form of such electric heater and its support in a tunnel 23 is disclosed and claimed in my Patent No. 2,226,526 issued December 24, 1940. I do not, however, desire to be limited to this specific form of electric heating element and its mounting on the no part of my I provide a main thermal heater control switch 25 .responsive to the temperature of the water in the lower part of the tank and here shown,

for illustrative purposes, as comprising a tubular member 21 secured to the wall of the tank II in a fluid-tight manner, to be positioned within the tank. The switch includes also a substantially rigid contact arm 29 and a resilient contact arm 3| which latter is normally yieldingly biased into engagement with arm 29 but; is adapted to be moved out of engagement therewith by an expansion rod 33 positioned in the'tubular member 21. While I have shown a specific form of thermal switch I do not desire to be limited thereto since any other thermally actuable switch responsive to tank water temperature may be used instead 01. the form shown.

I wish to point out also that while I have shown given positions 01' the thermal switch and of the single heater, I do not desire to be limited thereto and the thermal switch 25 is to be considered as being effective to cause disengagement of contact arms II and 29 when substantially all of the water in the tank is hot.

For purposes which will hereinafter appear, I provide an upper auxiliary thermal switch 35 including a tubular member 31, a relatively rigid contact arm 39, a resilient contact arm 4| normally yieldingly biased into engagement with arm 39 but adapted to be moved out of engagement therewith by the action of an expansion rod 43 positioned in the tubular member 31. The

general construction and operation of the thermal switch is substantially the same as that of the main thermal switch 25, the main difierence being-o! course, that the auxiliary thermal switch 35 will interrupt the engagement of arms 35 39 and H when it is subject to the temperature a mass II of heat-insulating material surround- 01' hot water at an upper part of the tank. While I have shown the thermal switch 35 as positioned substantially at half the height of the tank, I do not desire to be limited thereto, since it may be mounted in the upper one-third part of the tank or somewhat lower than the position in which it is shown so that the amount of hot water in the tank afiecting the auxiliary thermal switch will vary accordingly.

I provide further a continuously operative timing means 45 which includes a continuously operating synchronous motor 41 electrically connected to supply circuit conductors 49 and SI. A worm gear 53 on the shaft of motor 41 engages so a worm wheel 55 which is mounted on a shaft 51.

The design, construction and operation of the parts of the timer 45 thus far described is that the worm wheel 55 and particularly the shaft 51 will be rotated through one complete turn in a day of twenty-four hours. It is, therefore, to

be understood that while I have shown this particular form of continuously operative timer, other constructions effective for the same desired purpose may be utilized.

The shaft 51 has mounted thereon a cam disc 59 which cam disc has a peripheral portion 6| thereof ofsomewhat larger outer radius than the other portion of the disc. The peripheral extent of the portion BI is that corresponding to the desired length of an off-peak period and I have shown this duration as that of eight hours. It is to be further understood that the disc 59 may be adjustably mounted on shaft 51 so that the start and therefore the end of an off-peak period, will be that considered proper by the engineers of the central power station supplying electric energy to the supply circuit conductors.

I may provide a second portion 63 having the same outer radius as the portion 65 but extending over a shorter duration and if as indicated by the numerals on disc 59, the main ofi-peak period extends from 1:00 a. m. to 9:00 a. m. the portion 83 is shown as extending from 1:00 p. m to 4:00 p. m. I provide further a plurality of peripherally spaced lugs or projections 65, 5'!

' but moved into engagement therewith when a lug ll of electric-insulating material on the arm 75 engages the parts ti, e3,t5, t! and $9 of the disc 59 during the rotation of the disc in a clockwise direction, as shown by the arrow on the disc,

I provide further a control member I9 in the form of an electromagnetic contactor or switch including a coil 8i adapted to cause magnetization of a core member 89 having connected therewith a contact bridging member 85 which is adapted to engage a pair of fixed contact members it? all in a manner well known in the art.

Supply circuit conductor 99 is connected through a conductor 89 to one of the contact members ti? and to contact arm 15. Contact arm l3 is connected by a conductor M to the other contact member ti and also to one terminal oi coil ill. The other terminalof coil iii is connecwd by a conductor 93with contact arm ill. The other contact arm 39 of the auxiliary thermal switch is connected by a conductor 95 to contact arm oi the main thermal switch 226 which is also connected to one terminal of tank ll shall contain, during the daylight hours of a twenty-iour hour day, at least a predetermined minimum amount of hot water and that the tank shall contains. full charge of hot water at the start or the daylight hours. The parts of the system and particularly of the continuously operative timer, are shown in the-positions which they will respectively occupy at the start of an ctr-peak period at 1:00 a. m. At this time the main timer-controlled switch ll will be closed and assuming that there is an appreciable part thereof, an energizing circuit will be closed through the heater 2| as follows: From supply circuit conductor 49, through conductor 89, through engaged contact arms 15 and I3. through conductors 9| and 91 through the heater 2!, through engaged contact arms 29 and 3| and from there through conductor 99 to the other supply circuit conductor 5|.

Assuming further that the amount of cold 5L, Thi will cause upward movement of conamount of cold water in the tank in the bottom tact bridging member 85 into engagement with the fixed contact members 8'! and current may flow through the engaged contact members 85 and 81 and through the rest of the circuit since, as will be evident from Fig. l of the drawing, the contact members of the electromagnetic switch I9 are connected in shunt circuit relation to the contact arms 73 and I5.

If it should happen that the amount of hot water in the tank at the start of an oil-peak period was suficient to surround the tubular member 35 at the start of an off-peak period, the above described energizing circuit through coil 8! would not have been established, since contacting arm ill would be out of engagement with contact arm 39 but this would not have any effect upon the energization .of heater 2|.

The energization of heater 2| during the oilpeak period will continue until substantially all of the water in the tank is hot at which time the main thermal switch 25 will cause disengagement of contact arm 3| from contact arm 29 with resultant deenergization of the heater 2!. It may be pointed out that should this deenergization be efiected early during the course of an ofi-peak period and should withdrawals of hot water occur from the tank during the rest of the off-peak period, reenergization of the heater 20 will occur, all in the manner set forth hereinbefore.

When a cam disc 59 has the daytime portion 68 of disc 59 provided thereon, it may be considered to mean that the early aiternoon load on the central station is relatively light and that the operators of the central station consider it ad= visable to provide a second or secondary oi2= peak period defined by the portion t3 of the disc to ensure that the tank ll will contain more than the predetermined fractional part of hot watercontent provided in accordance 'with the position of the auxiliary thermal switch 35 to meet the probable larger demands for hot water in the later a ternoon and in the early evening.

When the first lug 5'5 engages member ill on contact arm 75 at say 7 :00 p, m, the main timeractuated switch it will be closed momentarily or for a short period of time only and the hereinbefore described energizing circuit through cell til will be established if'the upper thermal switch 35 is subject to the temperature of cold water surrounding it, that is, the tanlr ll contains less than a predeterminedfractional amount of hot water relatively to its total content. A holding circuit will be established through coil 96 after course, obvious that disengagement of contact arms 15 and I3, when lug 65 is moved out of engagement with lug 17 to cause disengagement of arm 15 from arm 13. This holding circuit is as follow From supply circuit conductor 49 through conductor 89, through engaged contact members 81 and 85, through coil 8|, through conductor 93, through engaged contact arms 4| and 39, through conductor 95, through engaged contact arms 29 and 3| and from there through conductor 99 to the other supply circuit conductor 5 I. It will be noted that this holding circuit is independent of the main timer-actuated switch H and is controlled by the two thermal switches 35 and 25.

It is evident that if the tank H contained a quantity of hot water less than enough to surround the upper thermal switch 35 at the time that lug 65 engaged the main timer-actuated switch II, energization of the heater 2| would continue until the auxiliary thermal switch 35 is subject to hot water with resultant disengagement of contact arm II from contact arm 39 and deenergization of the heater.

I have shown two additional lugs 61 and 69 positioned on the disc 59 to engage member 11 of the timer-actuated switch H at 9:00 p. m. and

at 11:00 p. m. and the same actions will be effected at these later times as has hereinbefore been described as occurring at 7:00 p. m. It is, of should the tank contain enough water to surround the upper thermal switch 35 at 7:00 p. m., 9:00 p. m., or 11:00 p. m., with attendant disengagement of contact arms II and 39, no energizing circuit through heater 2|, as above described, would be eifected. In other words, if the tank H contains at least a predetermined amount of hot water, the electric heater will not be energized.

Referring now to Fig. 2 of the drawing, I have there illustrated a. slightly different cam disc Il having an oil-peak disc are those which the disc may be considered to occupy in a selected position on the shaft and this oil-peak period is shown as extending from 12:00 midnight to 8:00 a. 111. Further, in-

the disc "H, the times corresponding to these lugs being shown as 1:00 p. m., 4:00 p. m., 8:00 p. m., and :00 1:. m.

In order to provide relatively simple and easily adjustable means on a cam disc, I may point |0| may be made of any suitable material, either metallic or fibrous, having a peripheral surface or constant diameter. Lugs or ears or the kind shown generally by elements 65, 61 and 59 or by elements I05, I01, I09 operatively associated with the individual disc by any suitable or desired securing means and the ctr-peak period peripheral portions of larger outer radius may be merely in the shape or arcuate strips, either resilient or pre-i'orrned, ot the desired duration-effect also easily secured against the periphery of the disc to extend over the desired periods.

Reference may be here. made to my copending application Serial No. 365,919, filed November 26, 1940, assigned to the same assignee as is the present application, wherein I have disclosed and claimed the water heating system which is shown herein, not as a part oi the present invention,

but adapted to be controlled by remotely located means, for example, in a central power station. The above described continuously operative timing means is therefore effective, when applied to a water heating system of the kind referred to herein, to ensure that the ordinary domestic hot water tank will contain at least a predetermined mimmum quantity of hot water during the daytime hours and that the tank will be substantially full of hot water at the start 'of the daytime period of a day of twenty-four hours.

Various modifications may be made in my invention without departing from the spirit and scope thereof and all such obvious modifications clearly coming within the scope of the appended claims shall be considered to be covered thereby.

I claim as my invention: l. A water heating system for a hot water tank having a single electric heater adjacent the lower end of the tank, comprising a continuously operative timer, a heater control switch, timer actuated means for selectively causing momentary closure and continuing closure of said switch at different times oi day, an electromagnetic heater control switch, a thermally actuabie switch responsive closure of the timer actuated switch causing energization of said heater through said electromagnetic switch in case said thermally actuable hot or to cold water.

2. A water heating system for a hot water tank having a single electric heater adjacent to the lower end of the tank, comprising a main and an auxiliary heater circuit, a single control switch for both circuits, a continuously operative timer, means driven by said timer for selectively causing momentary closure of said control switch at tank is hot.

3. A water heating system for a hot water tank having an electric heater, comprising a main thermally actuable heater-control switch responsive to tank water temperature and adapted to mally open switch, an able switch responsive to tank water temperature at an intermediate part or the height of the tank, electric circuit connections between the auxiliary and main thermally actuable switches and the electromagnetic and normally-open switch, a continuously-operative timer and a cam disc caused to rotate once in a day and effective to cause momentary closing of the normally-open heater-control switch at one part of a day-to effect energization of the heater through said main thermally actuable switch and the electrothereby and to continue the energlzation of the heater until the auxiliary thermally actuable switch is engaged by hot water, said cam disc being effective also to cause closing 01 the normally-open heater-control switch at another part of a day and to hold it closed for a preset length of time to efiect energization of the heater through the main thermallyactuable switch and the normally-open heater-control switch in case of the presence of cold. water in the tank, said heater energization continuing until substantially all of the water in the tank is hot.

i. A water heating system for a hot water tank having a single electric heater adiacent to the lower end of the tank, comprising a main thermally actuable heater-control switch responsive to tank water temperature and held in closed position until substantially all of the water in the tank is hot, a second heater-control switch in series circuit relation to said main thermally switch, a second ther-.

actuable heater-control mally actuable switch responsive to tank water temperature in an upper part of the tank, a continuously operative timer, a normally-open switch adapted to be closed momentarily at difierent times of a day and for an extended nerioci of time during anotherpart of a clay icy the timer and electric connections between all oi said. switches to cause a momentary closure oi said normally-open switch by the timer to he iolntly effective with saicl second thermally act-Liable switch to cause closure oi said second heatercontrol switch and energizatlon oi the electric heater in case the second thermally actuable switch is responsive to the temperature of cold water, said enersiaation continuing until said second thermally actueble switch is responsive to the temperature of hot water.

5. A water heating system for a hot wamr tank having a single electric heater adjacent to the lower end of the tank, comprising a main thermally actuable heater control switch responsive to tank water temperature and held in closed position until substantially all of the water in the tank is hot, an electromagnetic heater-control switch in series circuit relation to said main thermally actuable heaterecontrol switch, a second thermally'actuable switch responsive to tank water temperature in an upper part of the tank, a continuously operative timer, a normally open switch adapted to be closed momentarily at different times of a day and for an extended other period of time during a day by the timer and electric connections between all of said switches to cause a momentary closure of said normallyopen switch by the timer to be jointly efiective with said second thermally actuable switch to cause closure of said electromagnetic heatercontrol switch and energization of the electric heater in case the second thermally actuahle switch is responsive to the temperature of cold water. said energization continuing until said second thermally actuable switch isresponsive to the temperature of hot water and to cause a continued closure of said normally open switch to be jointly effective with said main thermally actuaole switch to energize'the electric heater i case less than the entire water content of the tank. is hot and to continue the enereization of the heater during all of said extended period of time in case less than the entire water content of the tent: is hot before the end of said. ex-

tended period of time.

6. A water heating system for a hot water tanlz having a single electric heater adjacent to the lowerencl of the tank, comprising a main thermally 'actuable heater-control switch responsive to tank water temperature anti held in closed position until substantially all of the water in the tank is hot, an electromagnetic heater-contrcl switch in series circuit relation to said main thermally actuahle heater controi'switch, a seconcl thermally actuahle switch responsive to tank water temperature in an upper nart of the tank,

a continuously operative timer, a ncrmally open switch adapted to he closed momentarily at clififerent times or a clay and for an extended other period of time during a day by the timer and electric connectiom between all of said switches to cause said second thermally actuable switch to prevent closure of said electromagnetic heatercontrol switch and energization of the electric heater on a momentary closure of said normally open switch by the timer in case the second thermally actuable switch is responsive to the temperature of hot water.

CLARK M. OSHEL'D. 

